[Ref: OpenBSD 5.0, Nagios 3.3.1, Nagios Core 3.x Manuals]
After you’ve hounded the web for how to install and configure Nagios for your system, check-out the definitive Project Documentation Note that the web often spews incorrect, misleading, misinformed datapoints.
These evolving guides are around OpenBSD 5.0 and Nagios 3.3.1.
If you are relatively new to Nagios, then I suggest that our install be in the following steps:
Although the Install/Configuration process is relatively simple, a new person to monitoring will get a lot of insight into how/what Nagios does for you by studying the Console/command-line tools and the Logs
The flexibility of Nagios is it’s huge cost. But once you get the time, and can get through the learning curve, you will have an amazing tool.